Art of tawing hides or skins



UNITED STATES PATENT OFFICE.

WILLIAM ZAlilN, OF NEWARK, NEW JERSEY.

ART OF TAWING HlDES OR KlNS.

SPECIFICATION forming part of Letters Patent No. 511,007, dated December19, 1893.

Application filedMay 27, 1893- Serial No. 4%,684- (No specimens.)

To all whom it may concern:

Be it known that 1, WILLIAM ZAHN, a citizen'of the United States,residing at Newark, in the county of Essex and State of New Jersey, haveinvented certain new and useful Improvements in the Art of Tawing Hidesor Skins; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same.

My present invention has reference more particularly to anew andimproved process of tawing skins or hides for the purpose of making kidleather, the present process being an improvement over my former processof tawing hides, described in my application for Letters Patent of theUnited States filed October 13, 1892, Serial No. 448,759.

This invention relates more especially to a novel process for tawingskins or hides, and consists in subjecting the skins or hides to theaction of certain metallic compounds, which are ofiered to the skins intwo dififerent baths, and whereby, by exposing the skins or hides to theaction ofthe chemical compositions, the leather is rendered, not onlywatar-proof, soft and flexible, but a leather of higher superiority inquality is the result, than leather made by other similar processes.

In order that a clear understanding may be had of my present inventionand the manner in which the same is to be put into practice, I will nowgive a description of the same.

For preparing the skins or hides and producing a strong, flexible andwater -proof leather in a much shorter time than heretofore, I subjectthe skins or hides, after the raw hide has been prepared in the ordinarymanner for tanning, to two baths. The first bath consists of a weak,preferably a one-half per cent. solution of chromic acid or itsequivalent. The previously prepared hides or skins are placed in thissolution, and after they have been left therein from one to three hoursor more, according to the thickness of the skins so as to be thoroughlyimpregnated by the solution, they are removed therefrom and drained andthe surplus water is pressed out. The skins or hides are thentransferred to the second bath, which consists essentially.

of a chromic oxide salt and a sulphide of an alkali or a suitablesulphide of an earth alkali. For the chromic oxide salt I prefer to usechrome alum and for the sulphide I may use sulphide of sodium orsulphide of potassium. The hides or skins are left in this bath from tento fifteen hours according to their thickness, and are then removed,washed, and'finished in the ordinary manner.

The liquor in which the skins are placed may be analyzed after theirremoval and brought to the proper concentration required, when the bathscan be used for the treatment of the second batch of skins or hides, aswill be evident.

The leather produced in this manner is very soft, elastic, strong andwater-proof.

Of course I am aware that some of the substances named herein above havebeen used before,but never before, to my knowledge, in the combinationherein above described, and the sulphide of an alkali or earth alkalihas not been used before for the purposes herein set forth.

Having thus described my invention, what I claim is 1. In the art oftawing skins or hides, the herein described composition consisting ofchrome alum, sulphide of sodium and sulphide of potassium, substantiallyas set forth.

2. In the art of tawing skins or hides, the herein abovementioned-composition consisting of chrome alum, and a sulphide of anakali or earth alkali, substantially as set forth.

In testimony that I claim the invention set forth above I have hereuntoset my hand this 22d day of May, 189-3.

WILLIAM ZAHN.

Witnesses:

WM. H. CAMFIELD, J r., FREDK. O. FRAENTZEL.

